Screening and evaluation of saline–alkali tolerance in a foxtail millet mini-core germplasm. Lignin as a protective barrier alleviating saline-alkali damage in foxtail millet. Under saline-alkali conditions, crops experience the dual stresses of high salinity and high pH. However, over the past few decades, the majority of researches focused primarily on plant responses to salt stress alone, leaving a limited understanding of how crops respond to combined saline-alkali stress and the underlying resistance mechanisms. In this study, we conducted large-scale screening of 458 accessions from a foxtail millet ( Setaria italica ) mini-core germplasm collection under mixed sodium saline-alkali stress and identified extreme tolerant and sensitive lines. Compared to sensitive varieties, saline-alkali-tolerant accessions accumulated higher levels of lignin, soluble sugars, and proline, but lower levels of malondialdehyde (MDA). These adaptive adjustments thus enable salt-tolerant varieties to undergo minimal transcriptomic reprogramming under stress. Furthermore, enhanced lignin deposition, triggered by SAPK10 overexpression, contributed substantially to plant resistance to saline-alkali stress. Collectively, our study identified promising germplasm and pinpointed lignin-mediated physical defense as a key strategy for saline-alkali tolerance in foxtail millet.
Li et al. (Sun,) studied this question.