Restriction Enzyme Analysis of Tomato Chloroplast and Chromoplast DNA

Abstract

Plastid DNA was isolated from the chloroplasts of tomato (Lycopersicon esculentum var Traveler 76) leaves and the chromoplasts of ripe tomato fruit. Comparisons of the two DNAs were made by restriction endonuclease analysis using PvuII, HpaI, and BglI. No differences in the electrophoretic banding patterns of the restricted plastid DNAs were detected, indicating that no major rearrangements, losses, or gains of plastid DNA accompany the transition from chloroplast to chromoplast.Central to the ripening process in tomato fruit is the transition of chloroplasts in the green fruit to chromoplasts in the ripe fruit.In this process the morphology and biochemical activities of the plastids are profoundly altered. The granal thylakoids characteristic of chloroplasts degenerate and carotenoid inclusions form (5,13). Chl is lost and photosynthetic activities cease, whereas synthesis of carotenoid pigments increases dramatically (12).Chloroplasts contain DNA which encodes proteins functional in photosynthesis and protein and RNA components of the plastid protein synthesis apparatus (2, 17). Other plastids also contain DNA, sometimes in quantities greater than chloroplasts of the same plant (15). However, the role of plastid DNA in the function of these organelles is not known.This study addresses the question of whether changes in the plastid DNA are involved in the transition from chloroplast to chromoplast. Plastid DNAs were isolated from the leaves and from the red-ripe fruit of tomato. These DNAs were digested with restriction enzymes PvuII, HpaI, and Bgl I, and the electrophoretic banding patterns of the fragments were compared. Any rearrangements or other changes in plastid DNA that occur during the plastid transition would alter the pattern of restriction endonuclease cleavage sites and be detected as a change in size of restriction fragments. In previous work, Iwatsuki et al. (6)

Plastid DNA in Developing Maize Endosperm

“…2 and 3) indicated that the maize endosperm plastid genome was indistinguishable from, and likely identical to, the maize chloroplast genome. The lack of distinguishable differences at the restriction site level is consistent with studies of nongreen plastids in pepper and tomato fruit, daffodil flowers, sycamore cell cultures, and wheat endosperm (2,7,11,15,22,24 (17, unpublished data); in addition, endosperm cell division is completed and the nuclear DNA copy number increases substantially (14).…”

“…Based on restriction endonuclease digestion patterns, amyloplasts of wheat (Triticum aestivum L.) endosperm (2) and sycamore (Acer pseudoplatanus L.) suspension cells (22), as well as the pigmented chromoplasts of tomato (Lycopersicon esculentum L.) (11,15,20), pepper (Capsicum annuum L.) fruit (7), and daffodil (Narcissus pseudonarcissus) flowers (32) contain genomes indistinguishable from the respective chloroplast genomes.…”

Chromoplast-Targeted Proteins in Tomato (Lycopersicon esculentum Mill.) Fruit

“…The isolation of tomato chromoplasts has been reported by others (Iwatsuki et al, 1984;Bathgate et al, 1985;Hunt et a]., 1986; Wrench et al, 1987), but we were unable to isolate pure and intact fruit chromoplasts that withstand the handling required to demonstrate successful import. However, in vitro import of an amyloplast-specific protein into chloroplasts (Klosgen et al, 1989) and the in vivo import of a chloroplast protein into nongreen plastids in transgenic plants (deBoer et al, 1988) implied that chromoplast proteins should also be imported into pea chloroplasts.…”

DNA polymerase activity of tomato fruit chromoplasts

“…; is chnr~tctcrizcd by the disnppcarancc of chloroplasts (cp) and the formation of non-photosyt~tl~ctic chromoplasts (cr). CI diffcrcnriation involves a number of morphological and biochemical changes, including starch degradation, breakdown of chlorophyll and thylnkoid mcmbrancs, and synthesis and accu~~ulation of cnrotenoids 111, In addition, photosynthetic proteins and their corrcspondinp mRNAs arc absent or greatly diminished [2,3], These changes in the patterns of gene cxprcssion are not due to major recombination4 arrangements of the pt genomc, since restriction patterns of cp-and crDNAs are identical in tomato [2,4, §], and other s$ccics [6,7].…”