Salinity responses in 24 guar genotypes are linked to multigenic regulation explaining the complexity of tolerance mechanisms in planta

Abstract

Guar (Cyamopsis tetragonoloba (L.) Taub.) is an economically important, droughttolerant legume crop affected by moderate to high salinity. Guar has various industrial applications, including gum extracted from seeds that is widely used in the oil and natural gas industries. In this investigation, we evaluated the salinity tolerance of different guar genotypes and their relation to genetic mechanisms regulating guar responses to salinity stress. We screened 24 guar genotypes in a greenhouse lysimeter system under control (electrical conductivity (EC) = 1.46 dS m −1 ) and high salinity (EC = 13.65 dS m −1 ) treatments. Both length and biomass of shoots were significantly affected by salinity compared to roots, indicating higher shoot than root sensitivity to salinity. Twenty-four genotypes were classified based on salt tolerance index for each trait. Tissue ion analysis revealed that roots accumulated over 10-fold higher Na than leaves, demonstrating that guar effectively regulated the root-to-shoot movement of Na + . However, higher Cl concentrations in leaves than roots indicated less regulatory control of Cl − movement. Based on the morphological traits and tissue ion analysis, six genotypes (PI 164486, PI 253186, PI 26152, PI 158125, PI 179926, and PI 263698) with different responses to salinity were selected for gene expression analysis. Expression patterns of different genes showed that a complex network of component traits, including Na + exclusion, Cl − exclusion, and tissue tolerance, regulate salinity tolerance in guar. Hence, the genetic information about different component traits will benefit guar breeders in developing new varieties that are more tolerant to salinity than current ones.

Strategies for combating plant salinity stress: the potential of plant growth-promoting microorganisms

“…Conversely, barley shows no yield loss with EC e = 8 dS m −1 , a 25% yield loss with EC e = 13 dS m −1 , and a 50% yield loss with EC e = 17 dS m −1 ( Amacher et al., 2000 ). It should also be noted that the salinity tolerance level of different cultivars of a specific species to salinity may show variation in responses and yields as observed in guar, alfalfa, and other crops ( Sandhu et al., 2017 ; Kaundal et al., 2021 ; Sandhu et al., 2021 , Sandhu et al, 2023 ).…”

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“…Recent studies by B. Acharya et al (2022) and D. Sandhu et al (2022) have shown that guar gum can be produced at lower prices than imported gums and produce lower greenhouse gas emissions than existing crops. Given the widespread use of guar and its products in the national economy and the high purchase prices, Ukraine should not be dependent on its imports, considerably saving currency assets.…”

Growth and Performance of Guar (Cyamopsis tetragonoloba (L.) Taub.) Genotypes under Various Irrigation Regimes with and without Biogenic Silica Amendment in Arid Southwest US

“…Recent studies have shown that guar gum can be produced at lower prices than US import prices and produce lower greenhouse gas emissions than existing crops in the Southwest US [8]. Salinity tolerance of guar genotypes is another advantage that can improve its adaptability in the Southwest US [9][10][11].…”

“…Due to its potential as an alternative crop in the Southwest US and a renewed interest in guar production, research on various aspects of guar production has recently gained impetus in the Southwest US [9][10][11][12][13][14][15][16][17]. A few recent studies have focused on the response of guar to irrigation level and shown the adaptability of guar under deficit irrigation conditions [18,19].…”