Physiological characteristics and transcriptomic analyses of alfalfa root crown in wintering

Area of Science:

• Plant Science
• Molecular Biology
• Agronomy

Background:

• Alfalfa (Medicago sativa), known as the "king of forages", relies on its root crown for winter survival.
• The specific molecular mechanisms conferring cold hardiness to alfalfa root crowns remain largely unelucidated.
• This research addresses the knowledge gap concerning the genetic basis of alfalfa's winter hardiness.

Purpose of the Study:

• To identify genes and molecular pathways associated with cold hardiness in alfalfa root crowns.
• To compare the cold hardiness and physiological responses between two distinct alfalfa cultivars under low-temperature stress.
• To elucidate the relationship between gene expression profiles and physiological changes related to winter survival.

Main Methods:

• Regional field experiments were conducted using two alfalfa cultivars, Longmu 806 and Sardi.
• Low-temperature treatment was applied, followed by RNA sequencing (RNA-Seq) to identify differentially expressed genes (DEGs).
• Winter survival rate (WSR) and physiological characteristics (jasmonic acid, soluble sugar, proline, glutathione) were analyzed.

Main Results:

• Longmu 806 exhibited a 3.68-fold higher WSR compared to Sardi alfalfa.
• Significantly higher concentrations of jasmonic acid (JA), soluble sugar (SS), proline (Pro), and glutathione (GSH) were observed in Longmu 806 roots.
• A total of 878 DEGs related to winter hardiness were identified, with several linked to plant hormone signaling, sugar metabolism, and glutathione metabolism pathways.

Conclusions:

• Specific genes, including MsERF1, MsCHIB, MsJAZ, MsAOC, MsGST, MsINV, MsTPS, and MsOAT, play crucial roles in alfalfa's cold hardiness.
• Enhanced concentrations of JA, SS, Pro, and GSH contribute to improved winter survival in alfalfa.
• The study provides a molecular basis for understanding and potentially improving alfalfa's adaptation to cold environments.