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US-20260125697-A1 - COMPOSITIONS AND METHODS USEFUL FOR THE REGULATION OF ABIOTIC STRESS RESPONSES IN HIGHER PLANTS

US20260125697A1US 20260125697 A1US20260125697 A1US 20260125697A1US-20260125697-A1

Abstract

Compositions and methods for creating plants exhibiting enhanced resistance to abiotic stresses, especially cold stress are disclosed.

Inventors

  • David Stern
  • Coralie Evelyn Salesse-Smith
  • Leila Feiz

Assignees

  • BOYCE THOMPSON INSTITUTE FOR PLANT RESEARCH, INC.

Dates

Publication Date
20260507
Application Date
20260105

Claims (9)

  1. 1 . A transgenic C 4 plant comprising heterologous, recombinant nucleic acids for expression of rubisco small subunit (SS), and ribulose-1,5-Bis-Phosphate Carboxylase/Oxygenase Accumulation Factor 1 (RAF1), increased expression of said SS, and RAF1 increasing holoenzyme accumulation, said plant exhibiting increased rubisco content, increased photosynthetic rate, increased biomass and enhanced resistance to abiotic stress when compared to plants lacking said heterologous nucleic acids.
  2. 2 . A transgenic C 4 plant comprising heterologous, recombinant nucleic acids for expression of rubisco small subunit (SS), and ribulose-1,5-Bis-Phosphate Carboxylase/Oxygenase Accumulation Factor 2 (RAF2), increased expression of said SS, and RAF 2 increasing holoenzyme accumulation, said plant exhibiting increased rubisco content, increased photosynthetic rate, increased biomass and enhanced resistance to abiotic stress when compared to plants lacking said heterologous nucleic acids.
  3. 3 . The transgenic plant of claim 1 , further comprising a heterologous nucleic acid encoding bundle sheath defective 2 (BSD2).
  4. 4 . The transgenic plant of claim 2 , further comprising a heterologous nucleic acid encoding bundle sheath defective 2 (BSD2).
  5. 5 . The transgenic plant of claim 1 , wherein said abiotic stress is cold stress.
  6. 6 . The transgenic plant of claim 2 , wherein said abiotic stress is cold stress.
  7. 7 . The transgenic plant of claim 2 , wherein said RAF2, and SS are operably linked to a ubiquitin promoter.
  8. 8 . The transgenic plant of claim 1 , wherein said RAF1, and SS are heterologous, recombinant nucleic acids are from the same or a different species of plant to be transformed.
  9. 9 . The transgenic plant of claim 2 , wherein said RAF2, and SS are heterologous, recombinant nucleic acids are from the same or a different species of plant to be transformed.

Description

This application is a continuation of U.S. patent application Ser. No. 18/512,898, filed Nov. 17, 2023, which is a continuation of U.S. patent application Ser. No. 15/371,185, filed Dec. 6, 2016, now U.S. Pat. No. 11,859,194, which is a continuation-in-part of International Patent Application No. PCT/US2015/034430, filed Jun. 5, 2015, which in turn claims priority to U.S. Provisional Ser. No. 62/008,913 , filed Jun. 6, 2014, the entire disclosures of each being incorporated herein by reference as though set forth in full. FIELD OF THE INVENTION This invention relates to the fields of genetic engineering and transgenic plants. More specifically the invention provides compositions and methods for regulating ribulose bis-phosphate carboxylase/oxygenase assembly and accumulation in higher plants, thereby altering abiotic stress responses and increasing photosynthetic activity in said plant. BACKGROUND OF THE INVENTION Several publications and patent documents are cited throughout the specification in order to describe the state of the art to which this invention pertains. Each of these citations is incorporated herein by reference as though set forth in full. Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the major enzyme by which green plants, algae, cyanobacteria and other autotrophic organisms sequester carbon dioxide into organic compounds via the Calvin-Benson pathway (Andersson and Backlund, 2008). Rubisco catalyzes the photosynthetic carbon reduction and the photorespiratory carbon oxidation reactions of the substrate ribulose-1,5-bisphosphate (RuBP) with CO2 and O2, respectively. The inefficiency of Rubisco in fixing CO2 has a limiting impact on agricultural productivity and in compensation, Rubisco accounts for as much as 20-30% and 4-9% of total nitrogen compounds in C3 and C4 higher plants, respectively (Feller et al., 2008). Attempts to improve the catalytic properties of higher plant Rubisco (reviewed in Parry et al., 2003; Mueller-Cajar and Whitney, 2008B) have met with only modest success, which can be traced in part to the lack of a comprehensive knowledge of its biogenesis and the absence of an in vitro reconstitution system. Form I Rubisco, found in higher plants, algae and cyanobacteria, is a hexadecamer composed of eight large (50-kDa) and eight small (13-15 kDa) subunits, denoted here as LS and SS, respectively. The genes encoding LS (rbcL) and SS (RBCS) are located in the chloroplast and nuclear genomes, respectively. SS is expressed as a pre-protein that is translocated into the chloroplast, where its signal peptide is cleaved prior to its assembly with LS (Nishimura et al., 2008). The two subunits accumulate stoichiometrically in the chloroplast, a phenomenon which is mediated by feedback inhibition of LS synthesis by unassembled subunits (Rodermel et al., 1996; Wostrikoff and Stem, 2007), as well as proteolysis of unassembled SS (Kanevski and Maliga, 1994). Attempts to delineate the assembly pathway of Form I Rubisco have exploited two major approaches; in vivo assembly of cyanobacterial Rubisco mainly using E. coli cells, and in vitro reconstitution of the enzyme via addition of individual components. In the first approach, assembly of Synechococcus PCC 6301 Rubisco in E. coli resulted in a functional enzyme (van der Vies et al., 1986; Tabita, 1999). LS was also expressed alone in this way, and shown to have minimal catalytic activity in the octamer form, which could be enhanced by the subsequent addition of SS (Andrews, 1988). Rubisco assembly requires multiple chaperones. The probable role of chaperonin (Cpn) 60 was first discovered through the co-purification of chloroplast Rubisco with a protein homologous to E. coli GroEL (Barraclough and Ellis, 1980). It was subsequently demonstrated that overexpression of E. coli GroEL-ES significantly promoted the assembly and activity of Synechococcus Rubisco in E. coli (Goloubinoff et al., 1989a). In fact, E. coli GroEL-ES and Mg-ATP proved to be the only factors necessary for the reconstitution of a catalytically active Rhodospirillum rubrum Form II Rubisco (Goloubinoff et al., 1989b However, only recently was Form I Rubisco assembled in vitro (Liu et al., 2010), which required both GroEL-ES and a small chaperone called RbcX (Larimer and Soper, 1993). RbcX appears to play a pivotal role in the solubility of LS and in vivo assembly of active holoenzyme in Synechococcus strains where the gene is located within the Rubisco operon (Onizuka et al., 2004; Emlyn-Jones et al., 2006;Saschenbrecker et al., 2007). In maize, the rbcX gene is expressed in leaves (Li et al., 2010), however the polypeptide remains to be detected in proteomic studies (Friso et al., 2010). Other than Cpn60, the only chloroplast protein shown to play a direct role in the folding or assembly of plant Rubisco is Bundle Sheath Defective 2 (BSD2), a DnaJ-like chaperone (Roth et al., 1996; Brutnell et al., 1999) with an unidentified mechanism of action. Although plan