Genetic and Proteomic Basis of Sclerotinia Stem Rot Resistance in Indian Mustard [Brassica juncea (L.) Czern & Coss.]

Abstract

Sclerotinia stem rot is one of the utmost important disease of mustard, causing considerable losses in seed yield and oil quality. The study of the genetic and proteomic basis of resistance to this disease is imperative for its effective utilization in developing resistant cultivars. Therefore, the genetic pattern of Sclerotinia stem rot resistance in Indian mustard was studied using six generations (P1, P2, F1, F2, BC1P1, and BC1P2) developed from the crossing of one resistant (RH 1222-28) and two susceptible (EC 766300 and EC 766123) genotypes. Genetic analysis revealed that resistance was governed by duplicate epistasis. Comparative proteome analysis of resistant and susceptible genotypes indicated that peptidyl-prolyl cis-trans isomerase (A0A078IDN6 PPIase) showed high expression in resistant genotype at the early infection stage while its expression was delayed in susceptible genotypes. This study provides important insight to mustard breeders for designing effective breeding programs to develop resistant cultivars against this devastating disease.

Genetic Analysis for Resistance to Sclerotinia Stem Rot, Yield and Its Component Traits in Indian Mustard [Brassica juncea (L.) Czern & Coss.]

“…The plots were paired rows of 4 m length with a 30 × 10 cm separation (row × plant). Except for any fungicidal treatment to reduce Sclerotinia stem rot, the entire recommended package and practices were followed to establish a healthy crop.The best environmental conditions for Sclerotinia stem rot epidemic development in Indian mustard include high relative humidity (>80%), a temperature range of 5 to 25 °C, and wet soil [ 1 ]. According to the weather data in Supplementary Table S1 , the crop’s field conditions were favorable for disease growth.…”

“…Using the techniques provided by Li et al [ 26 ] and Singh et al [ 1 ] a five-day-old pure culture of S. sclerotiorum was used to inoculate the main stems of 10 randomly chosen and labeled plants (other than the 10 representative plants selected for the assessment of yield and its component traits)from each genotype/replication. Mycelial discs (5 mm 2 ) were cut from the borders of pure culture plates, placed on a paraffin wax strip (together with a moist cotton swab) and wrapped tightly around the main stem, as in our prior investigations [ 1 , 6 ]. Lesion length (cm) was measured on each infected plant using a linear ruler at 20 days after inoculation for each genotype/replicate, and the average was taken.…”

“…Oilseed crops, just after cereals, play an important role in the Indian agricultural economy. India is on track to become the world’s third-largest consumer market and an importer of edible oils, meeting over 60% of its domestic consumption through imports at the cost of USD 10 billion per year [ 1 , 2 , 3 ]. Domestic demand for edible oils and fats has been proliferating at 6% per year, but domestic output has only increased by 2% per year.…”

“…Almost all plant parts are affected, including cotyledons, leaves, branches, raceme, siliquae, and stems, with infected tissue displaying typical white fluffy cottony mycelial growth symptoms ( Figure 1 ). On the other hand, infection of the stem causes girdling, which is linked to plant lodging and finally results in significant yield losses in Indian mustard [ 1 , 6 , 24 ].…”

“…Previous attempts to uncover resistant sources against Sclerotinia stem rot failed miserably because all Indian mustard genotypes tested were sensitive/highly susceptible, and whatever resistant sources were declared were connected to wild and other Brassicaceae species [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. However, in recent years, increased attention has led to identifying a few Indian mustard genotypes resistant to the disease [ 1 , 6 , 33 , 34 , 35 ].…”