I’m not sure about the tissues being smoother in off-colored areas in either RMV-symptomatic or variegated leaves; it could be an effect of either one, but this is a difficult time of year for me to check on something like that. Someone in a warmer climate might go investigating, though…
One way you could more positively identify true variegation is looking for the presence of “sheets” of tissue of different shades in different leaf layers. You might see several different colors - yellow, the original dark green, and perhaps one or two shades of in-between colors occurring in different patches (usually with patches of each color being pretty uniformly one shade and having fairly discrete edges that generally follow a vein… there’s very little smooth blending from one shade to another in most [non-disease-related] variegated plants I’ve seen). Also, there is a tendency toward a gradation of colors in adjacent patches - a patch of solid yellow will occur next to a patch of the in-between color, which itself is adjacent to normal green leaf sectors. Even when this occurs in a leaf, there are usually plenty of solid, bright colored sectors adjacent to dark green sectors. There probably will also be flecks of color within patches of other colors, too… it’s all somewhat random. It only makes some sense if you imagine one or a few cells mutating in the very early stage of leaf development, then multiplying and expanding to eventually represent different sectors of the leaf in patches of their respective colors.
Often you will find that the brightest colors - be they yellow (as in your case), cream, or white - occur in tissue on both the top and bottom of the leaf (and presumably in the mesophyll cells as well). Where there are intermediate colors, such as lime-green (as in your case), or grey-green (as is often found on cream- or white-variegated leaves), the off-color often occurs only in one layer of tissue (such as the leaf’s upper surface) and won’t be visible in that location if you flip the leaf over. The tissues are somewhat translucent, so the brightest variegation only shows up when there’s no green underneath it. That can be a useful way to test for true variegation.
I hope this hasn’t been too confusing… It really is hard to describe clearly. It’s one of those things where, once you’ve seen enough of it in real life, it’s easy to identify in person. Pictures can be a lot trickier…
Good luck with this; if it’s truly variegated, you could select cutting wood from more heavily affected branches until you have a (relatively) stable variegation going! The trait might also be heritable, although once you start selfing and back-crossing to get the variegated seedlings, you’ll still have a high percentage of solid green and total albino seedlings (the cute but deadly syndrome .
OH! Okay… I used a sideways carrot before “I’m” in the (now invisible) first paragraph at the beginning and it interpreted that as HTML code Oops. Here’s the message in more readable format with the original first paragraph:
–I thought I’d start a new thread to continue with Jim’s topic… See the “First draft - Can North American rose hybridizers safely use pollen from PNRSV infected roses?” thread for the original context of this discussion.–
One way you could more positively identify true variegation is looking for the presence of “sheets” of tissue of different shades in different leaf layers. You might see several different colors - yellow, the original dark green, and perhaps one or two shades of in-between colors occurring in different patches (usually with patches of each color being pretty uniformly one shade and having fairly discrete edges that generally follow a vein… there’s very little smooth blending from one shade to another in most [non-disease-related] variegated plants I’ve seen). Also, there is a tendency toward a gradation of colors in adjacent patches - a patch of solid yellow will occur next to a patch of the in-between color, which itself is adjacent to normal green leaf sectors. Even when this occurs in a leaf, there are usually plenty of solid, bright colored sectors adjacent to dark green sectors. There probably will also be flecks of color within patches of other colors, too… it’s all somewhat random. It only makes some sense if you imagine one or a few cells mutating in the very early stage of leaf development, then multiplying and expanding to eventually represent different sectors of the leaf in patches of their respective colors.
Often you will find that the brightest colors - be they yellow (as in your case), cream, or white - occur in tissue on both the top and bottom of the leaf (and presumably in the mesophyll cells as well). Where there are intermediate colors, such as lime-green (as in your case), or grey-green (as is often found on cream- or white-variegated leaves), the off-color often occurs only in one layer of tissue (such as the leaf’s upper surface) and won’t be visible in that location if you flip the leaf over. The tissues are somewhat translucent, so the brightest variegation only shows up when there’s no green underneath it. That can be a useful way to test for true variegation.
I hope this hasn’t been too confusing… It really is hard to describe clearly. It’s one of those things where, once you’ve seen enough of it in real life, it’s easy to identify in person. Pictures can be a lot trickier…
Good luck with this; if it’s truly variegated, you could select cutting wood from more heavily affected branches until you have a (relatively) stable variegation going! The trait might also be heritable, although once you start selfing and back-crossing to get the variegated seedlings, you’ll still have a high percentage of solid green and total albino seedlings (the cute but deadly syndrome .
I’ve looked at the leaf under magnification and it is as you describe for variegated leaves. Also, the difference in surface texture was much less than it appeared in the enhanced photo.
This seedling is a nice, but not very exciting, polyantha. It would certainly be more interesting with variegated leaves.
I like that seedling but then again Im a polyantha lover. I have a question about R. wichuraiana ‘Curiousity’. Is that a virus or…? it does look interesting and would look good on some landscape roses (as compared to other landscape plants). However, I do think it would look horrid on non-landscape types.
The variegation in Rosa wichurana ‘Curiosity’ is certainly somatic; it’s not caused by a virus. I agree, variegation can sometimes spice up an otherwise ordinary rose. One hybrid tea I’ve seen discussed on GardenWeb recently, ‘Verschuren’, has variegated foliage and looks good to me in photographs.
Jim, that’s still a pretty rose; it’s definitely worth a second look considering its potential for ornamental leaves! The gold variegation could pick up the warm glow in each flower’s center…
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