Development and Application of a PCR-Based Molecular Marker for the Identification of High Temperature Tolerant Cabbage (Brassica oleracea var. capitata) Genotypes

Abstract

Global warming accelerates the development of high temperature (HT)- and high humidity (HH)-tolerant varieties. This is further facilitated by the identification of HTHH-tolerant genes and the development of molecular markers based on these genes. To identify genes involved in HTHH tolerance in cabbage (Brassica oleracea var. capitata), we performed RNA-seq analysis of two inbred lines, BN1 (HTHH-tolerant) and BN2 (HTHH-susceptible), and selected trehalose 6- phosphate phosphatase I-2 (BoTPPI-2) as one of the HTHH-tolerant-associated genes. We also developed a segregating F2 population from a cross between BN1 and BN2. RNA-seq results showed that BoTPPI-2 transcript levels were high in the HTHH-tolerant inbred line BN1, but not detectable in the HTHH-susceptible inbred line BN2. The expression pattern of BoTPPI-2 was not related to the expression of heat shock-related genes. Soft rot resistance, used as an indicator of HTHH tolerance, was higher in BN1 than in BN2. F2 individuals similar to BN1 with respect to phenotype appeared to be HTHH-tolerant, whereas BN2-types were susceptible to HTHH. Analysis of the genomic DNA revealed the presence of a long terminal repeat (LTR; ca. 4.6 kb) in the ninth intron of the BoTPPI-2_BN2 allele, thereby suppressing its transcription and exhibiting HTHH phenotype. Except for the LTR insertion, the sequence of BoTPPI-2_BN2 was almost identical to that of BoTPPI-2_BN1. On the basis of the LTR and BoTPPI-2 sequences, we developed a molecular marker to identify HTHH-tolerant genotypes and validated its efficiency using F2 individuals, inbred lines, and cultivars from diverse sources. The marker explained the genetic basis of HTHH tolerance in at least 80%, but not 100%, of the cabbage genotypes. Thus, additional markers associated with HTHH tolerance are needed for perfect selection.

Trichoderma asperellum Inoculation as a Tool for Attenuating Drought Stress in Sugarcane

“…Although E and Ci values did not change by inoculation, sugarcane plants photosynthetically active and with stomatal conduction control showed higher WUE and carboxylation efficiency, since a higher rate of photosynthesis occurred for each unit of water that was evaporated by the stomata and CO 2 that was carboxylated in the biochemical phase of photosynthesis. Stomatal conductivity can be altered by inoculation with T. asperellum, since this microorganism acts as an abscisic acid producer (Poveda, 2020). Abscisic acid is an important phytohormone related to the modulation of stomatal opening-closure movement (Zargar et al, 2017).…”

“…An innovative technique increasingly studied and implemented in agriculture is the use of plant growth-promoting microorganisms (bacteria and fungi) to induce plant resistance to abiotic and biotic stresses (Zhang et al, 2016;Poveda, 2020). This approach is new and effective in increasing the plant tolerance to environmental climate challenges, which can play an important role in the development of sustainable agricultural systems (Rajesh et al, 2016).…”

“…There are countless species within the genus Trichoderma, and a highlight has been given to T. asperellum (Harman, 2005;De Sousa et al, 2020;Zhao et al, 2020). Several authors have reported the ability of this group of microorganisms to relieve biotic and abiotic stresses of germinating plants and seeds, reducing the damage caused by ROS (Poveda, 2020). However, the underlying mechanisms responsible for ROS scavenging have yet to be elucidated (Kashyap et al, 2017).…”