Turcicum Leaf Blight Resistance Screening and Combining ability studies in Maize

ACHARYA N.G RANGAAGRICULTURAL UNIVERSITY,
AGRICULTURAL COLLEGE,BAPATLA.
MASTER'S SEMINAR
TOPIC : Turcicum Leaf Blight Resistance Screening and Combining ability studies in
Maize (Zea mays L.)
COURSE NO : GP-591
DEPARTMENT : Genetics and Plant Breeding
SUBMITTED TO : SUBMITTED BY:
Dr.T.SRINIVAS,
Professor & Head, BAM/20-18,
Department of GPBR . Department of GPBR.
1
Agricultural College, Bapatla
Department of Genetics and Plant Breeding
D.Keerthana,

CROP
INTRODUCTION
ABOUT CAUSAL
ORGANISM
TLB SYMPTOMS
SCREENING FOR
TLB RESISTANCE
MANAGEMENT
COMBINING
ABILITY
CASE STUDIES
2
CONTENTS
Department of Genetics and Plant Breeding 2

Kingdom : Plantae
Division : Magnoliophyta
Class : Liliopsida
Order : Poales
Family : Poaceace
Genus : Zea
Species : mays
Binomial name –Zea mays
3

INTRODUCTION
Maize (Zea mays L.) is one of the important cereal crops and it is third
major crop in India after rice and wheat .
It has prominent position in the agricultural economy of the world both as
food for man and feed for animals.
It has yield potential far higher than any other cereal and is sometimes
referred to as the miracle crop or “Queen of cereals”
 It is a store house of energy with 65% starch, 12% protein and 6% oil and
the rest is accounted for husk and bran (fibre).
 It accounts for over 30% of global cereal output and still its demand
continues to soar. (Kumari et al., 2016)
4

Maize had assumed greater significance due to its demand for human
food, animal feed and industrial utilization.
Being a highly allogamous crop, it had been successfully exploited in the
production of hybrids which played a vital role in increasing acreage and
Productivity of Maize.
Maize being a C4 plant is physiologically more efficient, has higher grain
yield and wider adaptation over wide range of environmental conditions.
(Rajesh et al., 2018)
5

Statistics
AREA (million
hectares)
PRODUCTION
(million tonnes)
PRODUCTIVITY
(Kg ha-1)
INDIA 9.569 28.8 3006
A.P 0.3 2.05 6701
(www.indiaagristat.com 2019 – 20)
6

• Disease name : Turcicum leaf blight
• Casual Organism
Anamorph : Exserohilum turcicum
Telomorph : Setosphaeria turcica
• Period of occurance : Seedling to Maturity
ABOUT CAUSAL ORGANISM
7

In India, the disease was for the first time reported by Butler during 1907
from Bihar.
The disease is prevalent in almost all the maize growing areas in India.
Severe losses in grain yield due to epiphytotics have been reported in
several parts of India and these losses vary from 25 to 90 % depending
upon the severity of the disease.
The disease is responsible for premature death of blighted leaves and
results in significant yield reductions.
It is considered to be one of the most devastating diseases as it appears in
sizeable form in Karnataka resulting in reduction of grain yield of maize
by 28 to 91%.
8
Economic importance

 Mycelium is septate
 Conidiophores: single or in small groups, simple ,
olivaceous brown.They emerge in groups of 2-6
through stomata or directly through epidermis.
 Conidia : ellipsoidal to obclavate, pale to
olivaceous brown, straight to slightly curved, 4-9
distoseptate, germinate commomly from one or
both polar cells.
 Ascomata : black, globose to elliptical, ostiolate.
 Asci : cylindric – clavate , pedicillate, 1-8 spored.
 Ascospores: hyaline, 1-6 septate , constricted at
septa, straight to slightly curved.
9
Etiology

TLB Disease cycle
TLB DISEASE CYCLE
10

The disease starts at first as small elliptical spots on the leaves, greyish
green in colour and are water soaked lesions.
 The spots turn greenish with age and get bigger in size, finally attaining a
spindle shape.
 Individual spots are usually 3/4" wide and 2" to 3" long.
Spores of the fungus develop abundantly on both sides of the spot.
Heavily infected field present a scorched appearance.
 The disease is recognised by long elliptical greyish or tan lesions. When
fully expanded, the spots may be 1½" by 6" in size.
 These lesions appear first on the lower leaves and as the season
progresses, the lesion number increases and all the leaves are covered.
The plants look dead and grey.
(Hooda, K.S., Bagaria, P.K., 2018)
TLB SYMPTOMS
11

Fig : TLB Symptoms
12

13

• The TLB pathogens were isolated by collecting diseased maize leaf lesions from
experimental sites and placing in a moist chamber.
• After two-three days newly formed spores on the surface of the lesions was picked up
with the help of fine flattened needle under a dissecting microscope placed in a droplet of
sterile water and streak across the surface hardened, acidified water agar in petri-plates.
• After 6 hrs the spores start to germinate, and it was cut out of the agar and transferred to
hard, acidified PDA.
• After two weeks of incubation at 20oC-25oC, this culture was transferred to fresh plates
of acidified PDA for multiplication.
• When the fungus growth was covered the surface of petri-plate fully, the cultures were
ready for use.
• The spore (TLB) suspension at 60,000 spores/ml was applied in the whorl using atomizer
hand sprayers.
INOCULATION TECHNIQUE
14

• Inoculation was made twice a week for three weeks, when plants were 30-45 cm high
(at 4-5 leaf stages). After inoculation, water was sprayed with hand atomizer to create
favorable conditions for pathogen germination. (Alemayehu et al., 2018)
•
15

DISEASE RATING OF TLB
16

Rating
scale
Degree of infection (per cent DLA*) PDI** Disease reaction
1.0 Nil to very slight infection (≤10%). ≤11.11
Resistant (R)
(Score: ≤ 3.0)
(DLA : ≤ 30%)
(PDI: ≤ 33.33)
2.0 Slight infection, a few lesions scattered on two lower
leaves (10.1-20%).
22.22
3.0 Light infection, moderate number of lesions scattered on
four lower leaves (20.1-30%).
33.33
4.0 Light infection, moderate number of lesions scattered on
lower leaves, a few lesions scattered on middle leaves
below the cob (30.1-40%).
44.44
Moderately
resistant(MR)
(Score: 3.1–5.0)
(DLA : 30 – 50%)
(PDI: 33.34-55.55)
5.0 Moderate infection, abundant number of lesions scattered
on lower leaves, moderate number of lesions scattered on
middle leaves below the cob (40.1-50%).
55.55
17

(Chung et al., 2010; Mitiku et al., 2014)
*DLA- Diseased leaf area; **Percent disease index (PDI)
18
6.0 Heavy infection, abundant number of lesions scattered on
lower leaves, moderate infection on middle leaves and a
few lesions on two leaves above the cob (50.1-60%)
66.66
Moderately susceptible
(MS)
(Score: 5.1-7.0)
(DLA : 50.1 – 70%)
(PDI: 55.56-77.77)
7.0 Heavy infection, abundant number of lesions scattered on
lower and middle leaves and moderate number of lesions
on two to four leaves above the cob (60.1-70%).
77.77
8.0 Very heavy infection, lesions abundant scattered on lower
and middle leaves and spreading up to the flag leaf (70.1-
80%).
88.88
susceptible (S)
(Score: >7.0)
(DLA : >70%)
(PDI: >77.77)
9.0 Very heavy infection, lesions abundant scattered on almost
all the leaves, plant prematurely dried and killed (>80%).
99.99

19
Light Infection Moderate Infection Heavy Infection Very Heavy Infection
Fig: Diagrammatic Scale for assesment of TLB severity on Maize Plants:

• Disease assessment commenced 7 days after inoculation. Six assessments were made
at 7 days intervals from four central tag maize plants with visual observations and the
various parameters were recorded.
(Alemayehu et al., 2018)
• Severity scores were converted to percent disease index (PDI) as described by
Wheeler (1969) using the formula below:
Sum of numerical grading
Plants examined x maximum disease grade
X 100
PDI =
20

• The Htn1 locus confers quantitative and partial resistance against TLB by
delaying lesion formation.
• Htn1 was originally introgressed into modern maize cultivars from the
Mexican landrace Pepitilla in the 1970s.
• The Htn1 resistance reaction is different from the other known major TLB
resistance genes Ht1, Ht2, and Ht3, which confer qualitative resistance,
resulting in chlorotic-necrotic lesions.
• In contrast, Htn1 leads to a delay of sporulation without chlorotic lesions.
• The dominant and race-specific Htn1 gene is effective against the most
prevalent TLB races, but virulent isolates have been found. The strength of
the Htn1 resistance depends on environmental conditions and maize
genotype.
RESISTANCE GENES
21

Gene Source Inheritance Virulence
observed
Discovered by
Ht1 Ladyfinger(peru),
GE440(USA)
Dominant Yes Hooker, 1963
Ht2 NN14B(Australia) Dominant suppressed
by Sht l1
Yes Hooker, 1977
Ht3 Tripsacum floridanum Dominant Yes Hooker, 1981
Ht4 357(BS19, USA) Recessive No --
Htnl Pepitilla (Mexico) Dominant Yes Gevers, 1975
(Navarro et al., 2020)
Table : Resistant genes and their Sources

(Jakhar et al., 2019)
23
Fig : Physiological races of Pathogen Exserohilum turcicum:

Cultural practices :
Timely planting
crop rotation with non host plants
Chemical methods:
systemic fungicide : Propioconazole @ 350ml ha-1
contact fungicide : Mancozeb @ 2.6kg ha-1
Resistant varities:
BH-660 ; BH-540
Management
24
(Mitiku et al., 2012)

Combining ability in crosses is defined as the ability of parents to
combine amongst each other during the process of hybridisation, so that the
favourable genes are transmitted to their progenies.
1. General Combining Ability : used to designate the average performance
of an inbred line in hybrid combinations.
2. Specific Combining Ability : used to designate those cases in which
certain combinations do relatively better or worse than would be
expected on the basis of average performance of lines involved (gca).
* gca – measure of additive gene action and it helps in the selection of good
general combiners (parents) for hybridization.
COMBINING ABILITY
25

* sca - measure of non-additive gene action and it helps in the
identification of superior cross combinations for commercial exploitation
of heterosis.
• Combining ability is the effective tool in deciding the appropriate parents
for hybridization especially when a large no. of parental lines are
available and most promising ones are to be identified on the basis of
their ability to give superior hybrids.
(Adelardo et al., 2006)
26

S.NO PARTICULARS LINE x TESTER
ANALYSIS
DIALLEL ANALYSIS PARTIAL DIALLEL
ANALYSIS
1. Total crosses among ‘n’
parents
mf
m – no. of male
parents; f – no. of
female parents
n (n-1)/2 ns /2
s – sample crosses per
array
2. Components estimated D and H D and H D , H and I
3. Calculation Simple Difficult Difficult
4. Accuracy of results High High Medium
5. Efficiency Upto 50 parents 10-12 parents Upto 20 parents
6. Mating chances of parents as
male and female
Restricted Equal Restricted
ESTIMATION OF COMBINING ABILITY

28
CASE
STUDIES

Screening of inbred lines of rabi Maize for Turcicum leaf
blight (TLB) and Maydis leaf blight (MLB) in Bihar.
CASE STUDY 1
(Kumar et al., 2020)
29
International Journal of Bioresource Science
NAAS Rating:**

• The experiment was conducted for three consecutive years of 2017–18,
2018–19 and 2019–20 at research farm of Tirhut College of Agriculture,
Dholi, Bihar.
• 29 Maize inbred lines were evaluated against TLB and MLB diseases
seperately.
• The treatment was arranged following a randomized complete block design
(RCBD) with three replications, having spacing of 60 x 15 cm.
• Inorganic fertilizer (DAP, Urea and MOP) and all agronomic practices were
applied based on the area recommendations
Materials and Methods
30

• Inoculation was made twice a week for three weeks, when plants were 30-
45 cm high. The spores suspension at 60,000 spores ml-1 was applied in the
whorl using atomizer hand sprayers.
• Disease severity estimation of maize inbred lines were phenotyped for
TLB severity when the disease appeared using standard 1–5 scale, 1 being
complete resistant and 5 being the complete susceptible (Payak and
Sharma, 1982).
• Based on this rating scale maize inbred lines were categorized into four
groups namely
31
Disease Score Type of Resistance
<2.0 Resistant(R)
2.1-3.0 Moderately Resistant(MR)
3.1-3.5 ModeratelySusceptible(MS)
>3.5 Highly Susceptible(S)

Results and Discussion
32

Year Resistance inbreds Moderately resistance Moderately Susceptible Susceptible
2017-18 Dholi inbred – 2011, 2015,
2031 and 2038
S99 TLYQHGA 84-26 B.B.B ,DQL-2241
,DQL-2304 ,DQL-614-4, CML-470-
B4,MARSSSYN-155-2-1-1-BB,
DML1018, 2055, 2017, 2036, Dholi
inbred 2038, p72xBrasil 117,
DMRQPM 121, UMI-1205 (15)
DML-1846, DML-117, DML-
1828, IMLSB-46-1, IMLSB-106-
1, IMLSB-282-2, IMLSB-451-2,
IMLSB-561-2, UMI-1200.(9)
CML 186
2018-19 Dholi inbred – 2011, 2015,
2031 and 2035
S99 TLYQHGA 84-26 B.B.B , DQL-
2241, DQL-2304 , CML-470-B4 ,DML
– 1846 (BM2-11), DML – 1018 , DML
– 1828, DML – 2055, DML – 2017,
IMLSB -46-1 , Dholi inbred- 2038
,IMLSB -561-2, P72XBrasil 117, DQL -
614-4 , DMRQPM 121 , UMI -1205
(15)
MARSSSYN-155-2-1-1-BB,
DML-2036, CAL-14135, IMSLB-
46-1, Dholi inbred 2035,
IMSLB-282-2, IMSLB-451-2,
P72XBrasil 117, UMI-1200, CML
186.(10)
CML 186
2019-20 Dholi inbred – 2011 and
2015
Dholi inbred – 2031, S99 TLYQHGA 84-
26 B.B.B , MARSSSYN-155-2-1-1-BB,
DML-1018, 2055,2017,2036, CAL-
14135, Dholi inbred- 2038 ,2035,
DMRQPM 121, UMI-1200.(14)
DQL-2241 ,DQL-2304 ,CML-
470-B4, DML-1846 ,DML-117,
DML-1828, IMLSB-46-1,
IMLSB-106-1, IMLSB-282-2,
IMLSB-451-2, IMLSB-561-2,
P72XBrasil 117, UMI-1205.(13)
CML 186
33

• Local check line, CML – 186, showed susceptible during all three years
of study
• Overall, it was found that the inbred lines, Dholi inbred – 2011 and 2015
were resistant to the TLB disease for all three years of study.
Conclusion
34

Field screening of maize (Zea mays L.) landraces for resistance
against Turcicum leaf blight (TLB) under temperate conditions
CASE STUDY 2
(Dar et al.,2018)
35
International Journal of Chemical Studies
NAAS Rating:**

• 70 maize landraces were evaluated in an augmented design along with 3
checks KG-2 (susceptible check), SM- C4 (moderately susceptible) and
SM-C7 (resistant) at Mountain Crop Research Station, Larnoo, a hot spot
of Turcicum leaf blight in Kashmir during kharif season 2017.
• The test genotypes were planted in 2 row plots of 3m length with plant
spacing of 60×20 cm.
• The pathogen Exserohilum turcicum was isolated from infected leaves
using single spore isolation technique (Tuite, 1969).
• Total eight single spore cultures of E. turcicum isolated from diseased
samples of different locations were maintained on potato dextrose agar
slants.
Material and Methods
36

• Spore suspension of the E. turcicum from each isolate of 20 days old
cultures was prepared by washing the conidia with distilled water.
• Equal volume of spore suspension of 8 isolates was mixed and sprayed in
evening by using atomizer at three to four leaf stage of maize plants.
• Disease reaction was recorded by using 1 to 9 scale (of Indian Institute of
Maize Research, Ludhiana) commenced from 45 days after planting and
assessment of disease severity was continued on weekly basis for 6
weeks.
• Based on the rating scale genotypes are classified into 4 categories:
1.0–3.0 are resistant (R),
4-5 as moderately resistant (MR),
6-7 as moderately susceptible (MS),
8-9 as susceptible (S)
37

38

39

Conclusion
• Screening of maize landraces leading to the identification of TLB
resistant sources that holds a great promise in resistance breeding in areas
prone to TLB.
• The determination of genetic basis of these sources and incorporation of
their resistant genes into susceptible commercial cultivars is prerequisite
in the development of high yielding TLB resistant maize cultivars.
40

Combining Ability of White Maize inbred lines via Line X Tester
analysis
CASE STUDY 3
(Mousa et al., 2021)
41
Journal of Plant Production
NAAS Rating : 7.70

• The materials of the current study consisted of seven new white inbred lines of
maize i.e. Gz-8093, Gz-8092, Gz7253, Gz-7142, AED-7135, AED-6132, and
Tep-6420, developed at Ismailia Agricultural Research Station.
• In summer season 2016, the 7 inbred lines were top crossed to each of the
three testers single crosses SC10, SC128 and SC131.
• In summer season 2017, produced 21 crosses and the commercial check hybrid
i.e. TWC 324 were evaluated in replicated yield trails conducted at Ismailia,
Sakha and Sids Agricultural Research Stations.
• A randomized complete block design (RCBD) with four replications was used
at each location.
• Plot size was one ridge, 6 m long, 80 cm apart (4.8 m2 ) and hills were spaced
25 cm along the ridge.
42

• All agricultural practices were applied as recommended at the proper
time.
• Line x tester analysis was applied as described by Kempthorne (1957)
and as explained by Singh and Chaudhary (1985) to obtain information
about the combining ability of lines and testers as well as to estimate the
types of gene action controlling grain yield and other studied traits in the
tested lines.
43

44
Table 1 : Combined ANOVA across 3 locations for 21 crosses for 7 traits is presented in the below Table

45
Table 2: Mean Performance of 21 three-way crosses & one check for 7 traits across 3 locations
E
L
H
L
L
H
L
L
H
L
H M
L
L
H
From above results, two threeway crosses (Gz-8093 x SC 131 and AED 6132 x SC131) showed earliness and superiority for
grain yield and its components. This study recommended the future use of these crosses in maize breeding program.

46
Table 3: Estimates of general combining ability effects for seven inbred lines and three testers for seven
traits combined across three locations.
Note : Superiority of the single cross as good tester was reported by several investigators .

47
Table 4: Estimates of specific combining ability effects for 21 three-way crosses for seven traits combined
across three locations.

48
Genetic
Parameters
Days to 50%
silking (days)
Grain Yield
(ard/fed)
No. of ears/
plant
Ear
length(cm)
Ear
diameter(cm)
No.of rows
/ear
No. of
kernels
GCA 0.26 0.82 0.001 0.30 0.004 0.02 0.26
SCA 0.10 2.21 0.0001 0.19 0.003 0.04 0.42
GCA X Loc 0.18 1.50 0.0006 0.08 0.004 0.03 0.47
SCA X Loc 1.49 2.56 0.00004 0.20 0.008 0.34 0.68
Table 5: Genetic parameters and their interactions with locations for seven traits of maize combined across three
locations

 σ2gca > σ2sca : days to 50% Silking
no. of ears/plant
Ear length
Ear diameter
 σ2sca > σ2gca : Grain yield
no. of rows/ear
no. of kernels/row
Conclusion
49
Additive Variance plays a major role
in inheritance of these traits
non-additive gene effects are more
important than additive gene effects in
the inheritance of these traits.

Combining Ability and Gene Action Studies for yield and its
related traits in Maize(Zea mays)
CASE STUDY 4
(Rajesh et al., 2018)
50
International Journal of Current Microbiology and Applied Sciences
NAAS Rating :**

•The experimental material comprised of 15 lines and 3 testers, crossed in
Lx T design during rabi, 2010-11 at Maize Research Centre,
Rajendranagar,Hyderabad.
•45 maize hybrids along with their parents and 2 checks(DHM 115 , DHM
117)were evaluated in RCBD design with 3 replications for Combining ability
at Research farm, PJTSAU, Hyderabad during Kharif 2011.
•Each entry was raised in 2 rows with a row length of 4m and spacing
75 x 20 cm.
•All the recommended package of practices was followed to raise a good crop.
51

Results and discussion
52

If the ratio is closer to unity – greater the magnitude of additive gene action (gca) and vice
versa.
Here σ2sca > σ2gca indicating the predominance of non-additive gene action for all the
characters
53
Source Days to
50%
tasseling
Days to
50%
silking
Days to
maturity
Plant
height
(cm)
Ear
height
(cm)
Ear
length
(cm)
Ear
girth(cm)
Numbr
of
Kernel
rows/ear
Numbr
of
Kernels/
row
100
Kernel
weight
(g)
Grain
yield
(g per
plant)
σ2gca 0.0888 0.0508 0.0926 1.0228 0.9333 0.0180 0.0058 0.0046 0.0662 0.0214 3.0156
σ2sca 3.0310 4.2676 6.3765 195.304 63.1183 0.8203 0.5750 0.7777 3.4606 9.1159 289.028
σ2gca/
σ2sca
0.0292 0.0119 0.0145 0.0052 0.0147 0.0219 0.0101 0.0059 0.0191 0.0023 0.0104
Table 2: Estimation of gca and sca variance for yield and yield component characters in maize

S No SOURCE Days to
50%
tasseling
Days to
50%
silking
Ear
length
(cm)
Ear girth
(cm)
Number
of
kernels
per row
100
kernel
weight
(g)
Grain
yield (g
per
plant)
1 BM 5050 -0.99* -1.26** 0.87** 0.50** 2.36** 1.16** 20.62**
2 BM 1234 -1.32** -1.37** 1.27** 0.37* - 1.28** 18.17**
3 BM 3511-2 - - 0.47* 1.14** 3.23** 1.74** 16.07**
4 BM 3521 A-2 - - 1.01** 0.30* 1.21** - 12.93**
5 BM 5040 - - - - - 1.11** 6.80**
6 BM 5059 - - - - - 3.04** 6.66**
7 BML 10 -0.83** -0.68** - - - 0.48** 5.74**
8 BML 7 - - - - - - 0.98**
* Significant at 5% level ; ** Significant at 1% level
Table 3: Estimates of general combining ability effects for yield and yield component traits in maize
54

S No SOURCE Days to 50
%
tasseling
Days to
50 %
silking
Ear
length
(cm)
Ear
girth
(cm)
Kernel
rows per
ear
100 kernel
weight (g)
Grain
Yield (g
per plant)
1 BM 1234 x
BML 13
- -1.62* - 0.54* 0.86** 2.04** 13.83**
2 BM 3511-2
x BML 7
- - - 1.28** 1.04* - 13.55**
3 BM 5050 x
BML 7
-2.89** -2.95** 0.94** - - - 4.65**
4 BM 5050 x
BML 10
- - - - - 3.30** 4.17**
5 BM 1234 x
BML 10
- - - - - - 3.59**
* Significant at 5% level ; ** Significant at 1% level
Table 4: Estimates of specific combining ability effects for yield and yield component traits in maize

Conclusion:
 Both the parents with significant +ve gca effects
1.BM 5050 X BML 10
2.BM 3511-2 X BML 7
3.BM 1234 X BML 10
4.BM 5050 X BML 7
 BM 1234 X BML 13 – only one parent with significant +ve gca effects indicating the
involvement of additive x dominance gene interaction.
 The 5 hybrids with high sca effects for grain yield per plant can be used for the
development of single cross hybrids since non – additive gene action for most of the
traits was observed
56

THANK YOU
57

Turcicum Leaf Blight Resistance Screening and Combining ability studies in Maize

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